This invention relates to systems and processes for controlling scaling material in brine treatment systems that may be used to produce potable water, recycled water, processed water and the like. Conversion of brackish and saline water may include a primary treatment using a reverse osmosis or electrodialysis-reversal system and the concentrate brine stream produced may be further treated in an electrodialysis-reversal system to increase potable and other type water production and further concentrate the brine stream produced. The new system and method treats the concentrated brine stream loop to continuously remove calcium sulfate to reduce the scaling properties of the concentrated brine stream and to allow for higher treatment system recoveries.
Current brackish and saline water treatment systems and methods may use a primary process such as reverse osmosis (RO) or electrodialysis-reversal (EDR) process with a secondary process such as an EDR process to treat a brine stream produced by the primary process. The resultant further concentrated brine stream may be disposed or wasted, or further treated with a zero liquid discharge process. A major limitation of water recovery for the secondary process for the brine stream may be the fouling of the secondary system due to scaling of the EDR membranes due to elevated levels of sparingly soluble salts, such as calcium sulfate, in the brine stream. Current methods to control scaling may include brine stream pre-treatment with chemicals that may be toxic or may include limiting the recovery. Calcium sulfate may be found in the brine stream when sulfuric acid has been used for scale control.